Mallard (27), the Otago captain, will be in her third year in the squad while Hohepa (23), who scored eight tries for the Otago Spirit in five games this year, made her debut for the national side last year.
The Black Ferns beat Australia at home in two tests last year, but these will be the first games in Australia between the two teams since 2001.
Selection in the national squad is a welcome boost for the trio, especially after a disappointing season with the Otago Spirit which failed to make the semifinals for the first time.
Mallard played the last two games for Otago at hooker this season but said she had played most of her rugby at prop and was comfortable there.
She was pretty happy with her form, and felt her fitness had improved from last year.
Both Mallard and Hohepa have been doing plenty of work with trainer Andrew Keene.
The pair have spent time in the gym and have also been doing other work such as flipping car tyres and throwing medicine balls to improve their fitness.
"It beats going for a run, that's for sure," Mallard said.
Mallard, a PhD student in physiology at the University of Otago, started one test and came on as a substitute last year, and was keen to start in both tests this year.
She is the daughter of cabinet minister Trevor Mallard.
She said the Black Ferns were surprised by how competitive the Australians were last year and were expecting some tough games.
Hohepa is in her fourth year of playing rugby, and says she is getting better at reading a game.
Judging from her statistics she knows her way to the tryline.
She scored nine tries for the Otago side last year and backed that up by scoring five tries in two tests against Australia last year.
Deceptively quick, Hohepa hoped to get a start on the left wing for the Black Ferns.
Originally from Te Awamutu, she is in her final year of primary school teacher training at the University of Otago College of Education.
The Black Ferns assembled yesterday in Christchurch and travel to Australia later in the week.
The first test is in Canberra next Tuesday with the second test, also in Canberra, on October 18.
There are five new faces in the Black Ferns, who will be captained by Canterbury loose forward Melissa Ruscoe.
The team is coached by former Canterbury loose forward Dale Atkins.
Squad: Olivia Coady (Canterbury), Kendra Cocksedge (Canterbury), Monalisa Codling (Auckland), Fiao'o Fa'amausili (Auckland), Victoria Grant (Auckland), Victoria Heighway (Auckland), Hohepa, Rebecca Hull (Manawatu), Halie Hurring (Canterbury), Linda Itunu (Auckland), Emma Jensen (Auckland), Ruth McKay (Manawatu), Mallard, Huriana Manuel (Auckland), Hannah Porter (Auckland), Anna Richards (Auckland), Ruscoe, Kim Smith (Canterbury), Aimee Sutorius (Wellington), Doris Taufateau (Auckland), Stephanie Te Ohaere-Fox (Canterbury), Teresa Te Tamaki (Auckland), Shannon Willoughby (Hawkes Bay), Selica Winiata (Manawatu).